This invention relates generally to control means for adjustment of visible conditions in an environment which employs visual information and more particularly, to a novel apparatus and method for doing so employing optical imaging means.
Visual information provides an effective means to exercise control of environmental conditions in several respects. For example, a visual image of a building room being observed enables the spatial characteristics of visible objects therein to be determined as well as determining brightness levels (luminace) within said enclosure. It follows that a visual image for such building space provides both spatial and luminance information useful in controlling various lighting and other environmental conditions within the localized enclosure. Such visual image can be used as a means for regulating artificial illumination or natural illumination as well as detecting and responding to occupancy of such localized enclosure. In such type environment, processing of the acquired visual image enables control of artificial or natural light sources to be exercised for such purposes as work conferences, focused light projection, desk work and still other objectives. In other end applications of the same type, a pattern recognition concept is adopted whereby the acquired visual image can be employed for response to such varied conditions as intrusion, fire outbreak and power failure. Alarm means operatively associated with the latter type imaging process can thereby provide notice of such detected visible conditions within the building enclosure.
In U.S. patent application Ser. No. 07/263,023, entitled "A Photometric Device" filed Oct. 27, 1988, in the name of co-inventor, Mark Stanley Rea, there is disclosed solid state video camera means to acquire a visual image containing improved light (luminance) and spatial information. A measure of relative visual performance is determined by such means employing three stimulus variables contained in the captured image, namely, the age dependent adaptation luminance and apparent contrast of the target image against its background together with apparent physical size of said target image. Thus, said overall device carries out both image acquisition and image processing to still further include color discrimination or identification and to such an improved degree as to closely resemble that obtainable with the human eye. The illustrated photometric device is further said to include visual display means enabling a user to locate target objects in the particular space being viewed. As such, this device is said to comprise:
(a) a video camera having a pixel sensor array and known pixel value output signals relative to a black reference zero light value storage element in the sensor array, in response to the spatial-light intensity information being viewed by the camera, the camera having a low geometric distortion,
(b) filter means on the variable aperture lens for, in operation, transforming the camera spectral sensitivity to match a known spectral sensitivity,
(c) an image acquisition board connected to the output from the camera and having a spatial resolution closely related to that of the camera, the board having a dc restoration circuit for correcting any drift in the camera output signal, a pixel value programmable gain and offset amplifier, and means for storing the pixel values in digital form in a frame memory spatial array,
(d) a video target viewer connected to the camera, and
(e) means connected to the output of the image acquisition board for computing visual angle and scaling the pixel output signals for computing contrast from the absolute value in relation to a predetermined light intensity received by the camera, and providing a substantially constant and linear relationship capability between the input luminance and pixel value output signals over substantially the entire pixel sensor array and light range of operation.
It is desirable, as previously mentioned, to exercise control of many visible conditions occurring within the particular environmental space being regulated to include both closed and open spaces. It is further desirable to do so by central control means enabling remote devices to be automatically controlled responsive to visible conditions being observed. For example, such centralized control means can provide control of artificial illumination means for a room, such as incandescent, fluorescent and discharge lamp devices responsive to the localized lighting requirements, such as hereinbefore indicated, and do so in an energy efficient manner which accounts for natural light sources when applicable. It becomes still further desirable for such centralized control means to recognize visible conditions other than lighting levels and lighting locations which can occur within the particular spatial environment being regulated and respond to such localized parameters as intrusion and fire outbreak. Thus, while various centralized control systems are already known which can respond to all of the foregoing environmental conditions, it remains still desirable to exercise such control more effectively with control means making particular use of better visual information obtained from the particular spatial environment being regulated.